This research is designed to: (1) Investigate those enzyme systems related to the formation of dipalmitoyl phosphatidylcholine and other phospholipids which are important compositional and functional components of the pulmonary surfactant system. These include de novo palmitate synthesis, de novo phosphatidylcholine synthesis, acyl transferases, transacylases, N-methyltransferases and phosphatidylglycerol synthesis. (2) Investigate the synthesis of lung-specific proteins thought to be integral components of the pulmonary surfactant system and correlation of lipid and protein synthesis whereby these constituents form lipid-protein complexes. (3) Study the degradation of surfactant phospholipids by phospholipases to establish the role of these enzymes, integrated with other synthetic enzymes, in conferring fatty acid positional specificity to pulmonary phospholipids. (4) Study the above systems in fetal development with specific regard to growth of the surfactant system in utero. (5) Extend these studies to those conditions of particular interest in which the surfactant system is enhanced or inhibited, e.g., oxygen toxicity and adaptation, hypoxia, and administration of selected drugs and hormones. These systems will be studied in isolated and cultured type II cells, alveolar macrophage preparations, and in subcellular organelle fractions prepared from these cells from adult animals. Total lung fractions will serve as baselines for studies with isolated cells.